1. Field of the Invention
This invention relates to photographic apparatus and, more particularly, to improved motion picture rear projection viewer apparatus.
2. Description of the Prior Art
Rear projection viewer apparatus in which the projection system and the viewing screen are combined in a single structural unit are well known in the prior art. Among other advantages, this type of viewer apparatus provides a compact portable unit which permits satisfactory pictorial displays in normal ambient light conditions, and is particularly suited to those instances where available space is limited.
A highly compact, rear projection viewer designed for operation with a motion picture film cassette is described in U.S. Pat. No. 3,701,127 entitled "Projector Apparatus" and assigned to the same assignee as the present invention. The viewer unit described in the above-cited patent provides a highly compact unit employing a lenticulated viewing screen which for reasons of compactness is inclined rearwardly over the base of the apparatus. Inasmuch as the viewing screen is inclined, a screen arrangement is provided which directs transmitted images over a given viewing zone, displaced from the axis perpendicular to the screen. Such a viewing screen is described in U.S. Pat. No. 3,848,980 entitled "Projector Apparatus and System Employing Unique Screen" also assigned to the same assignee as the present invention.
Under some conditions of extremely high ambient light conditions, for example, viewing outdoors on an extremely sunny, bright day, the image on the screen of such a viewer may not be sufficiently bright for good viewing of the images projected thereupon. Also, the viewer/projector of the above-cited patent may be equipped to operate in a portable manner from a 12 volt source such as, for example, through a cigarette lighter outlet in an automobile or a portable battery pack or the like. Under some circumstances, again with probable high ambient light conditions, as illumination available from the 12 volt system may not be sufficient to provide good, bright viewable images under the conditions described.